Printed indicia for applying to items of clothing, such as T-shirts, sweatshirts, golf shirts, shorts, hats, and the like, as well as other cloth and paper goods, such as banners, posters, bags, flags, and the like, have become very popular over the last 20 years. Boutiques specializing in printing fanciful and textual indicia such as slogans, college names, sports team names and logos, licensed characters, and the like, on these various media, are commonly seen in stores across the country. The indicia available at these stores can be pre-printed on a substrate and applied with a heated press by operators at such boutiques to any of the aforementioned items purchased by a consumer, or they can be screen printed directly onto the items for later purchase.
In the screen printing process, a stencil screen is typically blocked (called "masked" in the industry) to embody the desired indicia and is then placed over the item to be printed. Ink of one color is then flooded onto the screen by a flood bar of conventional design. The ink may be of any type well-known in the industry for screen printing. After the ink is flooded onto the screen, the ink is squeegeed through the screen interstices onto the item, leaving ink of the desired color where the interstices in the screen are unblocked. The squeegee can be of any type known in the art.
Problems arise, however, when the printing is done upon a material, such as cotton, wool, paper, polyester, and the like, where contaminants are likely to adhere to the printing surface. The term "contaminant" is intended to be all encompassing and to include non-permanent material on the printing surface including, but not limited to lint, dust, dirt, synthetic or natural material fizz, human hair, cloth fibers, metal flakes, paint chips, and a variety of other undesirable debris capable of making its way onto a printing surface. These contaminants may be picked up on the printing screen and block previously unblocked interstices, causing imperfections on subsequent printing surfaces.
To correct this problem, two things must be done. First, the contaminant must be located and removed from the printing screen to prevent further printing imperfections. This is typically performed manually by the printing machine operator using a clean cloth or the tacky side of a length of tape. If the printing machine must be stopped, valuable printing time may be lost. Alternatively, if the operator attempts to locate and remove the debris during continuous operation, there is risk of injury to the operator and damage to the equipment.
Second, each of the printing surfaces containing an imperfection must be fixed or corrected. Depending upon the area, size, and shape of the imperfection, the operator or other personnel manually applies ink of the desired color to the spot with a suitable applicator. This approach requires the time of personnel who may be neglecting other duties in the printing process. Additionally, the intricacy of the printed indicia may be difficult to impossible to "touch up," leaving the item to be printed upon imperfect or ruined.
A few reasons for automatically removing contaminants from a printing surface are: (1) to allow printing machine operators to concentrate on other areas of printing; (2) to diminish the likelihood of ruining printed articles and printing screens; (3) to lessen printing machine downtime; and, (4) to reduce injury risk to printing machine operators.
In the printing field, several attempts have been made to develop methods and apparatus for cleaning printing devices. For instance, U.S. Pat. No. 4,905,596 to Kobler, is directed to a combined cleaning and safety device for a rotary printing cylinder. The device provides a cleaning arrangement including brushes for brushing against the surface of a printing cylinder to remove lint, dust, dirt and other contaminants. However, this type of printing is very different from the screen printing addressed by the present invention. U.S. Pat. No. 5,385,096 to Suzuki discloses a printing plate contaminant removing device for a printing press. The Suzuki invention uses a timing belt having a plurality of contaminant removal blades for scraping debris from a printing cylinder. This device is also very different from the present invention.
Likewise, U.S. Pat. No. 5,150,273 to Le Vantine discloses a device for removing dust, lint, and static charge from film and plastic surfaces. The Le Vantine invention also makes use of bristled brushes to sweep away the contaminants from the material surface. Le Vantine does not address the problems solved by the present invention, nor does the patent disclose the use of the invention with a screen printing machine.
Other contaminant removal devices, unrelated to the field of printing, include U.S. Pat. No. 5,553,344 to Rosenkrantz, disclosing a handled pick-up device; and U.S. Pat. Nos. 4,905,337 and 5,027,465, both to McKay, disclose rolling lint removers. None of these devices have been intended to address the long felt need for an automatic contaminant remover in the area of screen printing.